Ian Aikman and Gabriela Pomeroy
BBC News
Syria's leader Ahmed Sharaa has called for peace after days of clashes where Syrian security forces have allegedly killed hundreds of civilians from the Alawite religious minority.
The UK-based Syrian Observatory for Human Rights (SOHR) - which monitors fighting in Syria - said about 745 civilians were killed in 30 "massacres" targeting Alawites in coastal regions on Friday and Saturday.
The BBC has not been able to independently verify the death toll of the escalating violence, believed to be the worst since the fall of the Assad regime.
President Sharaa said: "We must preserve national unity and civil peace as much as possible and... we will be able to live together in this country."
Speaking from a mosque in Damascus on Sunday, the interim president said "what is currently happening in Syria is within the expected challenges".
Bashar al-Assad was overthrown last December after decades of repressive rule by his family and a 14-year-long civil war.
The number of fighters killed in the past four days brings the total death toll to more than 1,000 people, says the Syrian Observatory. This included about 125 fighters linked to the new Islamist-led government and 148 pro-Assad fighters.
Reuters news agency reported sources in the new Syrian government saying at least 200 of the fighters had been killed.
The violence of recent days was sparked after an ambush on government forces in the coastal region. A Syrian defence ministry spokesman described it as "treacherous attacks" against its security personnel, according to a report by the Sana state news agency.
It has since escalated into a wave of clashes between Assad loyalists and government forces.
Amid the fighting, hundreds of civilians have reportedly fled their homes in the coastal provinces of Latakia and Tartus - which were heartlands of deposed president Bashar al-Assad, who also belongs to the Alawite minority.
Alawites, whose sect is an offshoot of Shia Islam, make up around 10% of Syria's population, which is majority Sunni Muslim.
The violence has left the Alawite community in "a state of horror", an activist in the city told the BBC on Friday.
Large crowds sought refuge at a Russian military base at Hmeimim in Latakia, according to the Reuters news agency.
Video footage shared by Reuters showed dozens of people chanting "people want Russian protection" outside the base.
Meanwhile, local media reported dozens of families had also fled to neighbouring Lebanon.
The UN's special envoy for Syria, Geir Pedersen, said he was "deeply alarmed" by "very troubling reports of civilian casualties" in Syria's coastal areas.
He called on all sides to refrain from actions which could "destabilise" the country and jeopardise a "credible and inclusive political transition".